Need some help with my speedometer not working. Cruise control and the shift button on the steering wheel still work. I scanned the abs system and it was throwing a sign for a rear passenger abs speed sensor. Swapped it with a working sensor and speedometer started working again but if I go over 80mph the speedometer stops working. If I reset the sign it starts working again but stops if I go over 80mph. I’ve changed the used sensors about 2 times with both working ones. The sensors were tested thru tech stream. Any ideas what the issue can be. Codes are C0210 and C1223.
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Answer

 

At this point, the chances of the rear speed sensors being off is pretty much nearly ruled out. Inside the CV axles there is an ABS ring. The ABS ring and sensor act using the Hall effect, meaning if the ABS ring (also called tone ring) is busted it will not provide accurate readings for the sensor. Replacing the sensor only aided in increasing the signal strength, but once a certain frequency is passed it will no longer operate. Did the old ABS sensors have a lot of metal shavings on them? If this is also not the case, check all the connectors to the ABS module.

 

the old sensor did have sum spiky metal shavings that were cleaned off. Do you think attaching a small magnet to the speed sensor tip will maybe help get a stronger signal from the "worn" tone ring?

 

Not sure, and probably not worth the risk. If that magnet somehow gets unstuck it could fall into the tone ring and cause even more issues. From what I understand, the tone ring in and of itself can be replaced, instead of replacing the entire CV axle. Normally, there are going to be some spikey shavings just from wear and tear, but pieces fairly large in size are no good. If you can, take a peek down the sensor tube/housing in the hub when you have a chance and try and see if the tone ring bumps look thinned out or something of the like.

 

got it. Is it common for the tone ring to wear out? only have 130k miles. If it is the tone ring the mechanic shop will obv charge me to basically disassemble the axle and change the tone ring so it would make sense to just replace it but then again the axle is in good shape.

 

It's not common at all usually. It can happen though, through various circumstances. Usually somebody tinkers with the ABS sensor during a job (such as a rear shock job, some guys like to be SUPER careful) and something falls in, and then when the car is driven whatever fell in gets crunched up and it damages the tone ring. This is especially common in the north, as rust buildup on anything suspension related can get quickly out of hand.. If you replace the axle with the tone ring, it may actually end up being cheaper as there would be less labor involved. Out with one axle, in with a new one and then you have new axles and tone rings for around the same price as the work of getting the tone rings off and putting new ones on.

Keep in mind, your issues could be caused by something else, too.

 

Okay I think I am also going to be replacing my rear bearings bc I was reading up on another post and they said the bearing dust shield can also break apart inside and grind the tone ring down. By any chance do you know how hard it is to get the axle out. I was quoted 4.5 hours for 1 side. Also does the axle need to come out to change the bearing in the rear? Thank you for all your help

 

The entire axle does need to come out, yes. From my experience, it is probably somewhat more difficult than a FWD car's CV axle replacement job. Before you do that though, get a professional opinion on the ABS fault code. There may be a chance the rear axles and tone rings are totally fine, and that something else is electrically going wrong.

 

So I took the sensors out today for further inspection and maybe try to clean it. Attached are the pictures. The first one is the passenger side rear and I am pretty sure the tone ring is completely rusted out. I cannot even see the groves of the tone ring. The second picture is the rear driver side. The tone ring is sort of visible but is also worn down. I will be ordering new axles and bearings now. Thank you for all your help.

Passenger Rear Tone Ring

Driver Rear Tone Ring